Differential-pressure gage.



W. G. KENT & J. L. HODGSON.

DIFFERENTIAL PRESSURE GAGE APPLICATION FILED APR.25,1910.

Patented Oct. 17,1911.

WWII/E8358 INVENTORS Walter G Kent fiaflyzlmi JIM i John LHodgson UNITEDSTATES PATENT OFFICE.

WALTER GEORGE KENT AND JOHN LAWRENCE HODGSON, OF LONDON, ENGLAND.

DIFFERENTIAL-PRESSURE GAGE.

Patented Oct. 17, 1911.

and useful Improvements in Differential- Pressure Gages, of which thefollowing is a specification, reference being had therein to theaccompanying drawing.

This invention relates to gages adapted to be controlled by thediflerence between two pressures, and the object of the invention is toprovide a gage of this type which shall be very sensitive to a smalldifference of pressure, less sensitive to a large difference ofpressure, and incapable of being damaged by an overload or excess ofdifference of pressures.

With these and other objects in view, the invention consists of certainnovel features of construction, as will be more fully described andparticularly pointed out in the appended claims.

The accompanying drawing is a side elevation, partly in section, of somuch of an apparatus embodying our invention as.is necessary tounderstand the same.

The rincipal features of the device, are incloseki in a casing C, saidcasing forming also, as will be hereinafter explained, an essential partof the invention. The casing is connected by two pipes P and P with aconduit H through which aofluid is supposed to be passing. This conduitis shown as what is known as a Venturi tube such device being well knownin connection with fluid meters. The pipeP connects with the throat ofthe Venturi tube, while the pipe P connects with the up-stream portionof the tube or that portion from which the fluid is approaching thethroat. As is well known in connection with such 'Venturi tubes, thepressure at the point where the in the spaces between the disks which wei will now roceed to describe.

In the simplest form ofthe invention the gage might consist of a singlepair of corrugated isks or diaphragms J J, but in the a preferredembodiment illustrated we have shown five of such pairs of disks, twobeing illustrated in section and three in side elevation. The lower diskof each pair has its outer edge or flange bent over and crimped upon theouter edge of the upper disk of the pair as indicated at 1. In thecenter of each pair of disks and inside thereof are two thickened andrelatively stiif center pieces 7' j, the upper one of each pair ofcenter pieces having a threaded nipple.v 2 to engage a threaded hole 3in the lower center piece of the next pair of disks above it. Thenipple, however, of the uppermost center piece j enters a cap 4, whilethe lower center piece j of the lowermost pair of disks is coupled, asby a threaded nipple 5, with an opening in the bottom of the casing Cwith which opening the pipe P communicates.

To eifect tight joints between the different pairs of disks ordiaphragms we interpose washers 1' there being also a similar washerbelow the lowermost pair of disks.

Through an opening in the cap 4 a rod or wire J 3 extends, said rod orwire having a head at its lower end inside of the cap. Said rod or wireJ 3 leads through gland J 4 to the 'point or device where theaccumulated motion resulting from expansion or contrac tion of theseveral pairs of disks will be transmitted to a suitable device whichmay be a pointer p cooperating with a scale S to indicate the conditionsof expansion or con'- traction of the pair or pairs of diaphragms due tovariations of the pressure inside and outside of said pairs ofdiaphragms.

The casing is pressure tight, and to said casing is led the fluid fromthe main, while the pressure from the throat is conveyed to the interiorof the diaphra Owing to the fact that the structure 1s such that thegreater pressure is outside of the diaphragms, any excess of suchoutside pressure will only serve to collapse the diaphragms until thecenter pieces 7' and y" contact with each other in' the mannerillustrated in the drawing after which any further increase of outsidepressure can have no efl'ect upon the diaphragms and conse-w supporteddisks exposed to the pressure p the difference of pressure can causefurther motion.

It is to be understood that we do not limit ourselves to a plurality ofpairs of disks or diaphragms, since the invention in its simplest formmight embody only a single pair. But owi to the structure illustratedand described, the capacity can be increased to any amount by increasingthe number of pairs of disks which are connected together and threadedholes of the center p1eces. It is also to 'be understood that. we do notlimit ourselves to the scale and pointer employed for indicating theresults of the operation of the gage, since any other device that may bedesired may be substituted for the scale S and pointer p;

Having thus described our invention, what we claim is:

1. A device for measuring the difference of two fluid pressuresconsisting of a closed casing subjected to the greater pressure andcontaining a second casing having flexible walls subjected to the lesserpressure, the flexible walls being connected at their mary the nipplesgins and arranged to "contact against each other as the difierence'ofpressure increases, said contact progressing continuously from the outered e toward the center, whereby the increased external pressure willcause the contacting walls to support each other to prevent permanentdistortion, and an exhibitor actuated by the movement of said flexiblewalls.

2. A device of the character described comprising a casing, means forsupplying fluid under pressure thereto, flexible diaphragms supported insaid casing and united at their margins, means for introducing fluidunder pressure between said diaphragms, the walls of said diaphragmsbeing adapted to contact continuously from their margins inwardly whenthe external pressure is greater than the internal pressure, wherebysaid excess external pressurefwill cause the contacting portions of saiddiaphragms to support each other to prevent permanent distortion, and anexhibitor connected to said diaphragms.

In testimony whereof we aflix our signatures in presence of twowitnesses.

WALTER GEORGE KENT.

JOHN LAWRENCE HODGSON.

Witnesses:

H. D. JAMnsoN,

A. NUTIING.

